Earlier today, Landry told ABC News there is no crude oil spilling from the oil rig that sank after the massive explosion and fire, easing fears of a massive environmental disaster.

"We've been able to determine there is nothing emanating from the well head," Landry said. "That being said, we have positioned resources to be ready to respond should a spill occur... We will continue to monitor 24/7 for the next several days."

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Sunk Oil Rig's Environmental Impact

A relatively small slick of oil that spread from the rig right after the explosion had officials worried about larger spill.

On Thursday, oil officials feared the worst. "I think it could have the potential to be a major spill," David Raine, vice president of British Petroleum, the company who had the rig under contract, said.

Landry, however, said today that by using remotely operated vehicles and sonar, the Coast Guard determined that what oil is in the water was "residual from the explosion" and not the product of an opened well. Today that slick grew to 12 miles long, covering 100 square miles.

The Coast Guard launched vessels with "skimming" capabilities Thursday to help clean up that spill. Meanwhile four planes are scattering chemicals to disperse the oil, as well as 100 miles of containment booms designed to stop the oil from spreading.

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What Caused the Oil Rig Explosion?

Yet to our eye they seemed dwarfed by the size of the slick. Nonetheless, the Coast Guard is confident.

"Our hope is it will stay off shore," Landry said.

ABC News was able to survey the oil spill from a helicopter this afternoon. Although we were only allowed to fly within 9 miles of the sunken rig, the oil slick stretched well north of that boundary. Thick brown streaks blanket the water and there was a visible rainbow-sheen to the surface when the sun comes out. We watched as a tug and barge cut through the thick coating.

Although efforts are underway to contain and remove the oil, strong winds from the southeast threaten to push the oil slick north -- towards the Louisiana coastline just 50 miles away and fragile oyster fisheries and a bird sanctuary in the Mississippi Delta.

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Oil Rig Explosion Survivors Return to Land

BP and the company that owns the rig, Transocean Ltd., have other worries as several wrongful death suits have already been filed against the companies.

Search for Survivors Continues After Rig Slips Underwater

Nearly 100 survivors of Tuesday's explosion, which sent several workers diving off the 75-foot high platform, arrived in a New Orleans port early Thursday. Seventeen others were taken to area hospitals, some with critical injuries.

"My heart goes out to them, it really does," said Carol Moss, the wife of one survivor. "I couldn't imagine ... I just hope and pray that they find them."

After the Coast Guard fought a stubborn fire on the top of the rig for days, a series of explosions rocked the rig on Thursday before it eventually slipped below the water's surface.

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11 Missing After Oil Rig Explosion Off Louisiana Coast

"We were hoping to see the rig or any remnants, but it is completely gone," Coast Guard Ensign Mike Yanez said.

Official: 'Blowout' Possible Cause of Explosion

The Coast Guard said it is using underwater robots and working with survivors, BP and Transocean in the hope of determining the cause of the explosion.

"We have an active investigation that commenced with the start of this explosion," Landry said.

The rig was finishing work on a new well at the floor of the Gulf when it was rattled by an explosion late Tuesday night. The 115 survivors that have been accounted for said they scrambled from the burning rig, some piling into lifeboats, others jumping into the gulf, risking the more than 75-foot dive into the sea.

The rig is about twice the size of a football field and can drill up to 30,000 feet deep, according to Transocean's website.

Transocean's vice president, Adrian Rose, told the Associated Press Thursday the explosion appeared to be a blowout, meaning natural gas or oil forced its way up a well pipe and damaged equipment.

Right now there are 3,500 rigs operating in the Gulf of Mexico. Earlier this year President Obama announced he was opening more coastal waters in the Gulf and a vast area of the Atlantic, as well as northern Alaska. This accident is allowing critics of that decision to say "I told you so."